THE LYMPHATICS PRIMER

When I tell people that I do Manual Lymphatic Drainage, the reaction is normally one of intrigue and curiosity. Most people have a general idea of what the lymphatic system does, but its mechanisms and functions are still not well understood by the general public. Many physicians do not make it a priority to educate their patients about the lymphatic system (unless they are specialists in fields like oncology or physical therapy, dealing with damaged lymphatic systems). In the past few years, awareness of lymphedema, a condition resulting from the malfunctioning of the lymphatic system, has increased thanks in part to celebrities like Kathy Bates who speak publicly about their experience living with lymphedema. However, lymph is hardly a household word. My goal over the next two blog posts is to provide a very basic overview of how the lymphatic system works, what manual lymphatic drainage is and how it is beneficial not only to damaged lymphatic systems but also to support healthy systems.

The lymphatic system is a uni-directional filtration and transport network for fluids in the human body, responsible for maintaining fluid levels in balance. The three main functions of the lymphatic system are:

Immunological function through response of lymphocytes and other white blood cells to microbes, viruses and bacteria

Uptake of protein molecules and water from the intercellular fluid, filtration, and delivery of protein-rich lymph into the cardiovascular system

Absorption of fats and fat-soluble vitamins from the small intestine

A very basic anatomical explanation of the lymphatic system is as follows:

Superficial lymph vessels originate in intercellular spaces just below the skin surface and form an extensive plexus throughout the body. Fluid from the intercellular space, containing water, proteins, fats and other cells, is absorbed and transported along these pathways into regional lymph nodes. (The proteins absorbed by the lymphatic system are large molecules which are too big to be absorbed directly into the circulatory system – this is one of the reasons why the lymphatic system is so important, as it delivers the protein necessary for cellular functioning back into the bloodstream.) Deeper vessels transport lymph from the organs, and intestinal lymph vessels transport fluid called chyle from the intestines. Unlike the circulatory system, the lymphatic system has no pump. The fluid is moved along the vessels through intrinsic peristaltic contractions of lymphangions within the vessels themselves. The lymph travels through lymph nodes and deeper networks called lymphatic trunks to eventually drain into veins on either side of the neck, delivering the protein-rich fluid into the bloodstream.

The lymph nodes from a very important part of this process. As the lymph is transported through the lymph nodes, it becomes more and more protein-rich as water is reabsorbed into the body. In addition, lymphocytes and macrophages are stored in the lymph nodes, which are cells that engulf and expel bacteria, toxins and dead cells. This is how we fight infection. There are 600-700 lymph nodes in the human body, the majority of which are housed in the intestines, but the head and neck also contain a large concentration of lymph nodes. The other important node stations are the axillary nodes (in the armpit area) and the inguinal nodes (in the front crease area where the trunk meets the legs). In addition to the lymph nodes, the spleen, thymus and tonsils are also part of the lymphatic system, contributing important immunological functions. The spleen stores white blood cells and filters the blood of aged red blood cells. The thymus is particularly active in early development, as it stores immature lymphocytes, developing them to become T-cells which can later fight off pathogens and cancer. The tonsils are made up of tissue similar to lymph nodes and also help fight infection.

It is clear that the lymphatic system plays a critical role in homeostasis and immunological function, but how exactly does it work? Like most of the bodily systems, it has some very efficient features! The substances being transported through the lymphatic system at any given time comprise the lymphatic load. Lymph time volume describes how much of this load is transported over a period of time. The transport capacity is the maximum amount of lymph which can be transported over a period of time. The difference between the lymph time volume and the maximum transport capacity is the functional reserve, which normally provides the body a large amount of room for the lymphatic load to change, like a buffer. The body also has something called a safety function, which means the body can respond to an increase in lymphatic load by increasing its lymph time volume. In other words, if there is more fluid in the intercellular spaces, the body can respond by moving the fluid faster up until the transport capacity is reached.

There are several things which can increase the amount of fluid being transported, including exercise, heat, massage and inflammation (usually from infection). Poor venous return or congestive heart failure can also cause an increase in the lymphatic load. If several of these factors are at play, and the lymphatic load increases until the transport capacity is reached and exceeded, the result is swelling, or edema, from high output failure. The excess fluid is generally low in protein. For example, when I go running on a very hot day, sometimes my fingers swell. This is an example of high output failure. When the lymphatic system itself malfunctions, such as in the removal of lymph nodes or through oncological radiation, the transport capacity can decrease and eventually dip below the level of the lymph time volume. In this case, it is called low output failure and the result is lymphedema, or an accumulation of protein-rich fluid in the body. (Please check out a great blog on lymphedema by a woman living with the condition – https://thelymphielife.com/).

Having a well-functioning lymphatic system improves immune health, allergy resistance, vitality, and helps us to more efficiently detoxify the myriad of environmental pollutants that find residence in our bodies. In my next blog, I will explore how I use Manual Lymphatic Drainage to optimize the function of the lymphatic system.